Telephone-transmitter.



C. D. BABCOCK.

TELEPHONE TRANSMITTER.

APPLICATION FILED may, 1909.

Patented Oct. 5,1909.

Momma s UNITED STATES PArENT OFFICE.

CLIFFORD D. BABCOCK OF NEW YORK, N. Y., ASSIGNOR TO UNITED WIRELESSTELE- GRAPH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented Oct. 5, 1909.

Application filed April 17, 1909. Serial No. 490,555.

-State of New York, have invented certain new and useful Improvements inTelephone- T rausmitters; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to'which it appertains to make and use thesame.v

The present invention relates to a telephone transmitter, and has forits object the production of such a transmitter as will be exceedinglysensitive'in operation to faint sounds, and will at the same time becapable of transmitting by and in accordance with sound wavescomparatively large differences of electrical energy without anysparking being heard in the receiver.

It is well known that certain chemical compounds and mixtures ofcompounds have the remarkable property of changing their electricalconductivity to an abnormal degree upon a small increase of temperatureafter acertain critical temperature has been reached, and I takeadvantage of'this property to cause a current While passing through suchcompounds to be varied, all as will be more fully hereinafter disclosedand particularly pointed out in the claims.

j Referring to the accompanying drawings forming a part of thisspecification, in which like numerals refer to like parts in all theviows:Figure 1, is a diagrammatic illustration of one form of theinvention. Fig.

' 2, is a like view showing a modification in which oscillating sendingand receiving circuits are employed. Fig. 3, a further modificationshowing the sensitive conducting elements in series. Fig. 4:, anothermodification showing a telephone relay. Fig. 5, still anothermodification showing a sensitive flame as the heating means, and Fig. 6,a sectional view of a device employing a spiral 1 represents a sensitiveconducting element composed of any suitable chemical compound or mixtureof chemical compounds, such as certain oxids of the metals;

. certain chlorids; sulfids and certain iodids.

Cupric oxid CuO, ma esium oxid, plumbic oxid, the mercury sub imates,and even common glass may be mentioned as examplesof such suitablecompounds, and which are distinguished from other compounds by thefollowing properties :At normal temperatures their resistances are veryhigh, and as the temperature changes their conductivitiescorrespondingly change, until critical temperatures are reached, whentheir conductivities experience changes for very small changes intemperature, which are very greatly in excess of the increases ordecreases to be noted in their respective conductivities before thecritical point is reached.

2 represents any suitable source of current; 3 a circuit passing throughthe element 1, and 4 any suitable receiver.

5 represents a heating means, included in the circuit 7, supplied fromthe source of ductance 10 are included in the heating circuit 7, and acapacity l2'and an adjustable inductance 13 are included in the circuit3,

which .is also provided with a coil 14 by which the circuit 3 may beplaced in inductive relation with an aerial of a wireless telephone ortelegraph system. v

In Fig. 3, two sensitive elements are joined in series, and the sendingcircuit 3 1s shown as grounded.

' In Fig. 4, the sending circuit is the same as "in Fig. 1, but theheating circuit 7 is provided with any suitable variable contact device15 which may be actuated by a telephone receiver 16, which in turn maybe operated from a distant station.

Fig. 5, represents a sending circuit 3, as'

hol, the latter ignited, and while burning,

or even after being extinguished, the heat 'from the spiral maybe variedby the cooling action of sound waves directed on the element and spiralfrom the funnel 19.

, In all cases the operation is as follows The sensitive conductingelement 1 is raised to or above the critical temperature by manipulatingthe rheostat 20 or other suitable device controlling the quantity'ofheat delivered to the said element, and then the transmitter 8 or otherdevice 17 or. 19 is brought into action to vary the heat received bysaid element 1. The result is, greater variations of ener in the sendincircuit 3, than in the heating circuit 7, an consequently louder signalsat the distant station.

It is evident that this invention is capable of wide variation by thoseskilled in the art without departing from the spirit of the invention,and therefore I do not wishto be limited to the details disclosed,except as pointed out in the claims.

WVhat I claim is 1. In the art of transmitting speech, an element whoseelectrical conductivity is abnormally sensitive to small changes intemperature, when a given criticaltemperature is approached, andcomprising inits composition a chemical compound, substantially asdescribed.

'2. A member of a telephone transmitter comprising in its composition anoXid whose conductivity is abnormally sensitive, When a certaintemperature is approached, substantially as described.

3. A telephone transmitter provided with an element comprising achemical compound, whose conductivity is abnormally sensitive to changesof temperature, when a certain temperature is approached, and means forheating said element, substantially as describe 4:. A telephonetransmitter provided with an element composed of an oxid whoseconductivity is abnormally sensitive to temperature changes when acritical temperature is approached, and controllable means for heatingsaid element, substantially as described.

5. A telephone transmitter provided with an element comprising achemical compound whose conductivity is abnormally sensitive to changesin temperature, when a critical temperature is approached; a send-.

ing circuit passing through said element; a heating means for the same,and means for controlling said heating means; substantially asdescribed.

6. In a telephone transmitter the combination of a sending circuit; areceiver and an element whose conductivity is abnormally sensitive totemperature changes when a critical temperature is approached andcomposed of a metallic oxid included in said circuit; and means forraising said element to any desired temperature; substantially asdescribed.

7. In a telephone transmitter the combination of a sending circuit; areceiver and an element whose conductivity is abnormally sensitive totemperature changes when a critical temperature is approached, saidelement being composed of a metallic oxid included in said circuit;means for raising said element to any desired temperature comprising aheating circuit provided with a coil in proximity to said element; andmeans to control the current through said coil; substantially asdescribed.

8. In a telephone transmitter the combination of a sending circuit; areceiver and a conducting element composed of a metallic oXid includedin said circuit; means for raising said element to any desiredtemperatelephone transmitter in said heating circuit; means to actuatethe same from a distant station; and means to control the currentthrough said coil, substantially as described.

10. In' a telephone transmitter the combinationof a sending circuitprovided with a capacity and an adjustable inductance; a conductingelement sensitive to small changes in temperature in said circuit; aheating circuit for said element also provided with a capacity and anadjustable inductance, and a telephone transmitter in said heatingcircuit, substantially as described. y

In testimony whereof, I afiix my signature, in presence of twoWitnesses.

CLIFFORD D. BABCOGK.

WVitnesses J osnrH G. HUNT, CHAS. A. CONLON.

